BillVon or other techies: Arctic-grade WX stations?

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Skyeyes and I took jobs teaching K-1 in a rural school in bush Alaska. Our kids are really into weather and technology so we found a grant that will allow us to get them a internet-capable weather station, but we've hit a snag. The lowest-registering temp sensor we can find caps out at -55F and we know from locals that the temperatures here get below the -60F that their analog mercury thermometers will record.

We've tried contacting the university and NOAA for assistance but they either did not respond or had no knowledge about anything outside of the ultra-expensive AWOS/Scientific grade of instruments.

Can any of you guys/gals recommend a home or pro-am grade wx station that will both register below -60F and upload data to the internet?

"If you end up in an alligator's jaws, naked, you probably did something to deserve it."

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How handy are you with electronics? Can you (or someone you know) write a little software to upload data from a logger?

A simple Type J or Type K thermocouple is cheap; both measure quite accurately well below "brass balls" temperatures. Hook it up to a readily available USB logger and you're set.

A quick search showed that for under $100 including the thermocouple, this should do the trick:


You may be able to find similar solutions for cheaper if you spend a bit of time looking. Search for "USB thermocouple logger".

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>Can any of you guys/gals recommend a home or pro-am grade wx station that will
>both register below -60F and upload data to the internet?

The sensor itself is pretty easy. Thermocouples have a very wide range; type K (the most common type) works from −200 °C to +1250 °C. NTC thermistors, another common type of sensor, will easily go down to -60C. (C not F but -60C will definitely give you -60F.)

The problem is in the device that reads the temperature sensor. Resistance (NTC) type sensors get higher in resistance as the temperature drops, and at some point the device reading it will see a resistance so high that it assumes it is not connected. Other devices will limit the minimum temperature to -55C in software. Some will not (see last paragraph.)

Cheap n easy way to use a sensor directly is to use an NTC sensor and a digital multimeter. Measure the resistance, convert it to degrees F and you're all set - and you can do this for $40 or so. If you want to upload to the net get a webcam and point it at the display. Stupid I know but a lot of people do this and it's cheap and easy.

If you want to use an Internet station you can do tricks like putting a signal conditioner in front of the sensor input. For example, if you add a parallel resistor to an NTC sensor the 'effective' temperature will be moved upwards, so -55F would actually read as (say) -30F. There are problems at the top range, though.

A bit more complicated of a trick would use an amplifier to "compress" the range of the sensor down to a more manageable level. For example with not too much work you could compress the readings of either an NTC or thermocouple sensor down to half their nominal values - for example 0F is still 0F but -60F becomes -30F, +80F becomes +40F etc. That makes it easier to translate back to real values.

Finally, even though many stations claim they will work down to only -55F they may actually work much lower, although their accuracy will not be guaranteed. Thus you may be able to use an off-the-shelf system if you can take a test reading to see if it's really capable of reading down there. If it can read dry ice (-109F) then it will definitely work for you.

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